circle.pde

int mouseClickedCount = 0;
float mouseLastClickedTimeMS = 0;

Circle[] circles = new circles[100];
int circleIdx = -1;

boolean dragging = false;
int draggingCircleIdx = -1;
float draggingOffsetX = 0.0;
float draggingOffsetY = 0.0;

void setup() {
    frameRate(60);

    size(960, 800);

    addCircle(1, 10);
    addCircle(20, 10);
    addCircle(30, 10);
}

void draw() {
    background(0);

    drawCircles();
}

void mouseClicked() {
    float now = millis();

    if (now - mouseLastClickedTimeMS > 500) {
        mouseClickedCount = 0;
    }

    mouseClickedCount++;

    if (mouseClickedCount == 2) {
        mouseClickedCount = 0;

        addCircle(mouseX, mouseY);
    }

    mouseLastClickedTimeMS = now;
}

void mousePressed() {
    int i;
    float dx, dy;

    for (i = 0; i <= circleIdx; i++) {
        dx = sq(circles[i].x - mouseX);
        dy = sq(circles[i].y - mouseY);
        if (dx + dy < sq(circles[i].currentR / 2)) {
            draggingCircleIdx = i;
            draggingOffsetX = mouseX - circles[i].x;
            draggingOffsetY = mouseY - circles[i].y;
            dragging = true;

            break;
        }
    }
}

void mouseReleased() {
    dragging = false;
}

void addCircle(float x, float y) {
    circles[++circleIdx] = new Circle(25, x, y);
}

void drawCircles() {
    for (int i = 0; i <= circleIdx; i++) {
        if (i == draggingCircleIdx && dragging) {
            circles[i].x = mouseX - draggingOffsetX;
            circles[i].y = mouseY - draggingOffsetY;
        }
        circles[i].draw();
    }
}


class Circle {
    float r, x, y;
    float currentR;
    int dX, dY;
    String name;

    Circle(float r_, float x_, float y_, String name_) {
        _setup(r_, x_, y_, name_);
    }

    Circle(float r_, float x_, float y_) {
        _setup(r_, x_, y_, "A random name");
    }

    void _setup(float r_, float x_, float y_, String name_) {
        r = r_;
        x = x_;
        y = y_;
        currentR = 0;
        dX = random(2) > 1 ? 0.1 : -0.1;
        dY = random(2) > 1 ? 0.1 : -0.1;
    
        name = name_;    
    }

    void draw() {
        noStroke();
        if (sq(x - mouseX) + sq(y - mouseY) < sq(currentR / 2)) {
            fill(64, 128, 128, 100);
        } else {
            fill(255, 255, 255, 100);
        }
        ellipse(x, y, currentR, currentR);
        fill(10, 110, 2, 100);
        ellipse(x, y, 2, 2);

        if (currentR < r) {
            currentR += 0.5;
        }

        x += dX;
        y += dY;
        fill(255, 255, 255, 100);
        text(name, x - currentR, y - currentR);
    }
}